#include<stdio.h>
int main()
{
    int person,cars;

    scanf("%d",&person);
    if(person<0)
    {
        puts("Are you kidding?");
        return 0;
    }
    if(person%4==0)
        cars=person/4;
    else
        cars=person/4+1;
    printf("%d\n",cars);
    return 0;

}
